1. Field of the Invention
The present application relates to a flavour concentrate containing a diketone precursor.
2. Prior Disclosures
By diketone precursors are understood compounds that are converted under certain conditions, upon which conversion a diketone is formed. Diketones such as, for instance, biacetyl (2,3-butanedione) and 2,3-pentanedione are compounds which are commonly used for flavouring food products. Thus, biacetyl and 2,3-pentanedione are, for instance, added to margarines to give these products a butter-like flavour. In this application, by the term flavour both the smell and the taste impression are meant.
It has been found that during storage of diketone-containing food products the content of these compounds may decrease drastically with time, probably due to volatilization and/or reaction with other food components and/or oxidation. Besides, it has been found that, upon heating such diketone-containing food products, the diketones volatilize very rapidly, which volatilization is accompanied by the development of an unpleasant, penetrating smell. Moreover as a result of this rapid volatilization the flavour derived from the diketones, during heating, may disappear entirely.
The use of diketone precursors for flavouring food products has already been described in European patent specification EP-C 0 068 774 (Hercules Inc.). This patent specification describes diketone precursors (alpha-ketodiacyloxy compounds) which meet the following structural formula: ##STR3## in which R.sub.1 and R.sub.2 are C.sub.1 to C.sub.5 hydrocarbon radicals having a total carbon number of 2 to 10, or phenyl radicals, and R.sub.3 and R.sub.4 are C.sub.1 to C.sub.18 alkyl, cycloalkyl, alkenyl or aryl groups and R.sub.1 and R.sub.2, or R.sub.3 and R.sub.4, can be different groups.
In the European patent specification it is reported that, upon heating, these compounds are converted into a diketone and a carboxylic acid. The formation of a carboxylic acid is a disadvantage of the use of these precursor compounds as the formation of said compound may, for instance, adversely affect the pH of the food product, and moreover also its taste and stability.
Dutch patent application NL-A-7309647 (Unilever N.V.) describes the stabilization of dialkyl furenidones, which, in food products, upon storage and heating appear to be unstable, by converting them into corresponding addition products with ketones or aldehydes. These addition products are particularly suitable for addition to food products which are heated to temperatures above 100.degree. C. as they disintegrate on heating, releasing the free furenidone. In Example XII of this application, it is described how the addition product of a dialkyl furenidone and the flavour compound 4-cis-heptenal can be obtained, after which it is stated in Example XV that a frying fat containing this addition product acquires a butter-like character after heating to 150.degree. C.